Apparatus for transferring a plurality of smears

ABSTRACT

A method of transferring a substance adhering to the surface of a substrate to a receiving surface of a backing element which includes locating the substrate surface in juxtaposition with the receiving surface, supplying a transfer medium on the receiving surface in sufficient quantity to encapsulate the substance, joining the transfer medium on the backing element with a substance so as to encapsulate the substance within the transfer medium and removing the substrate to expose the encapsulated substance.

This is a continuation of application Ser. No. 642,421, filed Dec. 19,1975, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to apparatus for transferring a dried, fixed andstained smear of a biological substance from a substrate to a backingelement which provides a permanent mounting for the smear forexamination of the smear under a microscope.

2. Prior Art

There is disclosed in Adler U.S. Pat. No. 3,871,895 apparatus and amethod which may be automated for preparing a smear of a biologicalsubstance on a substrate. The smear may comprise a whole blood specimenor other type of cellular suspension. Such smears are useful forexamination of the cellular material for diagnostic purposes.

That technique, which utilizes a ribbon element, may be characterized asincluding the steps of supporting the substrate element for movement,supporting the ribbon element for movement in close proximity to thesubstrate element at a sample-applying station, introducing a relativelysmall quantity of a biological liquid sample between the ribbon andsubstrate elements at the sample-applying station, spreading the sampleacross at least the central portion of the ribbon element, drawing thesample on the substrate element by moving one of the elements relativelyto the other, and moving the ribbon element by advancing it to present afresh portion thereof to the sample-applying station. In the formillustrated there by way of example, the substrate is a flexible tapeand the patent details the manner in which such a smear-carrying tapeshould be at least temporarily assembled by manipulation with amicroscope slide for examination under a microscope with the tape inplace.

The present invention deals at least in part with the permanent mountingof a transferred smear on a microscope slide for such examinationwithout the presence of a tape or the like.

SUMMARY OF THE INVENTION

One object of the invention is to provide a permanent microscope-readybacking for a biological smear transferred intact in fixed and stainedcondition from a substrate on which the smear was prepared.

Another object is to provide such a transferred smear which isencapsulated in a clear, scratch-resistant material which permeates thecellular matter of the smear and has an index of refraction whichapproaches that of the cellular matter. Such scratch-resistant materialmay be an adhesive fixed to the backing or may be the backing materialitself which was previously softened in the appropriate smear-receivingarea by the application of a solvent to a surface stratum of thebacking.

There is provided an apparatus for transferring a biological substancesmeared and dried on a surface of a substrate to a smear-receivingsurface of a backing element which includes locating the substratesurface in juxtaposition with the receiving surface, supplying atransfer medium on the receiving surface in sufficient quantity toencapsulate the substance, joining the transfer medium on the backingelement with a substance so as to encapsulate the substance within thetransfer medium and removing the substrate to expose the encapsulatedsubstance.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a fragmentary somewhat diagrammatic view in side elevation ofapparatus embodying the invention;

FIG. 2 is an enlarged fragmentary view in side elevation illustrating aportion of the apparatus of FIG. 1 in an operating condition;

FIG. 3 is a view taken on line 3--3 of FIG. 2;

FIG. 4 is a broken, fragmentary, side elevational view diagrammaticallyillustrating sequential functions of the apparatus of FIG. 1; and

FIGS. 5, 6 and 7 are views taken on lines 5--5, 6--6 and 7--7,respectively, of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

There is disclosed in Adler U.S. Pat. No. 3,871,895 apparatus and amethod for preparing a smear of a biological fluid substance on asubstrate. In the illustrated form of that disclosure, a series ofdifferent blood samples are applied sequentially as smears in axiallyspaced condition along a common substrate in the form of a tape and thesmears are fixed, stained and dried. While in that illustration the tapeis shown as being cut into convenient sections each having a smearthereon, it will be evident that the tape may be collected on a take-upspool or fed directly into other apparatus for performing subsequentoperations on the smears. Such apparatus for performing other operationson the smears is shown in FIG. 1 hereof wherein the substrate or tapeissuing from a source, not shown, such as the apparatus of that patentfor example, is trained over an idler roller 12. The substrate or tape10 may be formed conveniently of Mylar resin, cellulose acetate,polyethylene or polypropylene for example. As best shown in FIGS. 4 and5 one of a plurality of such smears axially spaced apart on the tape isindicated at 14. Such smears are located on the tape surface remote fromthe tape surface in contact with the roller 12. The tape 10 passes fromthe roller 12 to a position intermediate a pair of driven pinch rolls 16and thence over a fixed platen 18 from which it is directed over anidler roller 20 and thence to a collection take-up spool 22 which isdriven, preferably continuously, in the direction of the arrow.

The apparatus includes a stationary upright housing 24 open at the topand having four side walls and a bottom and holding in verticallystacked relation a supply of smear-receiving backing elements 25 whichin the illustrated form are rigid and may take the form of microscopeslides which may be fed by gravity to the bottom of the housing 24. Thehousing 24 has a dispensing opening in one side near the bottom andthrough which the slides 25 are dispensed one after another, separatedby an interval of time, by a pusher 26 to a position intermediate thedriven pinch rolls 16 which are biased together in a conventionalmanner, not shown. The rolls 16 sandwich the tape 10 and each slide 25therebetween with the slide overlying a corresponding smear 14. Oncefree of the rolls 16, each slide 25 is carried by the traveling tapepassing over the platen 18.

A transfer medium is required to transfer the smears 14 to therespective slides 25 without altering their morphological or staincharacteristics. The medium is a substance producing adhesion betweeneach smear and the corresponding slide which is greater than theaffinity of the smear to the tape. Such a transfer medium may consist ofa liquid adhesive applied between each smear and the corresponding slideand which is subsequently cured in a manner appropriate to the selectedadhesive. Suitable adhesives will be discussed hereinafter.Alternatively, the transfer medium may be formed in situ on theunderside of the corresponding slide structured of a suitable plasticmaterial and consist of a solute in a tacky, semi-fluid state includingplastic material derived from the slide and a suitable solvent. Thistransfer medium or solute is formed by applying such solvent to theunderside of the slide. Inasmuch as it is necessary thereafter todissipate or diffuse the solvent to harden the transfer medium, suchdiffusion of the solvent is characterized hereinafter in the appendedclaims, largely as a matter of convenience, as "curing" of the transfermedium.

By way of example, there is provided a fixed receptacle 28 for a supplyof a liquid agent which may be the transfer medium including adhesivematerial in liquid form or which may be only a constituent of a transfermedium such as a liquid solvent. The receptacle 28 in practice is ofsubstantial cross section, open at the top to the atmosphere, and has anoutlet 30 at the bottom thereof coupled to one end of a rigid tube 32.The other end of the tube 32 is connected to the inlet of a fluidcoupling 34 which has a conventional pivotal spring-biased outletconnected to the inlet end of a rigid tube 36 to bias the tube 36 fromthe full-line dispensing position thereof of FIG. 1 to the broken-linenondispensing position thereof. As shown, the tube 36 has an upwardlydirected outlet position 38. In the nondispensing position of the tube36, the outlet thereof is at the same horizontal level or higher thanthe liquid level with the receptacle 28. However, as a slide 25 isejected from the housing 28 by the pusher 26, the slide contacts theoutlet portion 38 of the tube and deflects it in a manner to lower it tothe full-line position below such liquid level wherein liquid from thereceptacle 28 flows through the outlet to dispense a relatively narrowband of such liquid 40 on the lower surface of the slide as the lattermoves over the outlet in the manner best illustrated in FIGS. 2 and 3.

Each slide 25 with the applied liquid agent on the underside thereof ismoved one after another into registry with the tape 10 in such phasedrelation to a corresponding smear on the tape that the slide issuperimposed on the smear where the slide and the tape are broughttogether between the pinch rolls 16 before passing with the tape ontothe platen in the same superimposed relationship. For example, thesmears may be of a thickness of less than 0.0002 inch, a width of 0.5inch and a length of 2.75 inches, while the slides 25 may be of anyconvenient thickness, a length of 3.0 inches and a width of 1.0 inch. Aseach slide 25 is drawn into intimate contact with the tape by the pinchrolls 16, the liquid 40 on the underside thereof spreads as a coatingacross the slide to the extent indicated in FIG. 6, a distance at leastslightly greater than the width of the underlying smear 14. No pressureas such is required to transfer a smear 14 to a slide 25. Thecompressive force of the pinch rolls 16 need be only sufficient tospread the liquid 40 quickly in a thin, flat layer. On theaforementioned spreading of the liquid 40 by the pin rolls 16, theliquid permeates the smear 14 including cellular material thereof andencapsulates the smear. Such flow of the liquid 40 into a smear 14 isindicated in FIG. 4. Upon movement of the trailing edge of slide pastthe biased tube 36, the tube 36 is returned to the nondispensingposition thereof.

As previously indicated, the appropriate curing of the transfer mediumapplied or formed on the underside of the slide will depend upon thenature of the selected transfer medium. One class of suitable transfermedium includes a cyanoacrylate monomer adhesive which is polymerizablewithin 10-60 seconds by surface-adsorbed basic catalysts, such as water,producing a thin, flat, transparent, hard mass strongly adhering to theslide, having a scratch-resistant surface and a refractive indexapproaching that of the cellular material of the smear, in which thesmear is encapsulated and the cellular material thereof permeated bysuch adhesive. A second class of suitable transfer media includes anadhesive mixture of vinyl monomers or monomers and polymers, thepolymerization of which is initiated by a photocatalyst such as benzoin,benzoin ethers, benzil or Michler's ketone and with or without additionof a polymerization accelerator such as N, N dimethyl aniline, whenexposed to light of the appropriate wavelength, e.g. near ultravioletwhen benzil is used, producing a mass such as characterized above withreference to the first class. A third class of suitable transfer mediaincludes an adhesive mixture of vinyl monomers or monomers and polymers,the polymerization of which is initiated with a catalyst such as benzoylperoxide and with or without added amine accelerators, which when heatedproduces a mass such as characterized above with reference to the firstclass. A fourth class of suitable transfer media includes a solventwhich does not attack the tape but which softens and dissolves thesurface stratum of a plastic microscope slide producing an adhesivesemi-fluid layer which, when the solvent is diffused therefrom, forms amass similar to that described above with reference to the first classbut in which the mass is in fact an integral surface portion of theslide.

An example of a transfer medium of the second class comprises aphotopolymerizable adhesive mixture comprising 100 pts. (wt.) cycloxexylmethacrylate, two pts. (wt., benzoin ethyl ether, and three pts. (wt.)dimethyl aniline. This mixture was applied in an approximately 0.001inch thick layer between a smear on a Mylar tape surface and a glassslide and was polymerized in five minutes by irradiation at a distanceof one inch from the laminate by a 4 watt GE F4T5 ultraviolet lamp.

An example of a transfer medium of the third class comprises a thermallypolymerizable adhesive mixture consisting of 130 pts. (wt.)polyester-styrene solution sold as Duro brand resin for bonding glassfibers, and 1 pt. (wt.) methyl ethyl ketone peroxide catalyst mixturesold as Duro brand liquid hardener. This mixture was applied in a layerof approximately 0.001 inch between the smear on a Mylar tape surfaceand a glass slide and was polymerized in 5 minutes by heating at 60° C.

An example of a tranfer medium of the fourth class consists of a solutecomprising a solvent of ethylene dichloride for a surface stratum of anacrylic slide structured of Lucite which solvent does not attack a tapestructured of Mylar. This solvent was found to soften the appropriateportion of the surface stratum of the slide to at least a tackysemi-fluid state when applied in a layer less than 0.001 inch between asmear on such tape and such slide. The diffusion of the solvent, whichwas largely into the slide, was enhanced by exposure to heat at 60° C.over a period of 30 minutes.

In the form of FIG. 1, a lamp assembly spaced above the platen 18 forirradiation of the latter is indicated at 44. It is to be understoodthat the assembly 44 is provided as a source of heat or ultravioletlight for curing those types of transfer media requiring or enhanced bysuch treatment, and may be eliminated, together with the platen 18,where such treatment is not helpful in the use of the selected transfermedium. It will be apparent that while each laminate, comprising aportion of the tape 10, a smear 14 on the tape and a slide 25 overlyingthe smear with the transfer medium 40 against the underside of the slide(FIG. 4), travels over the platen 18 on the advance of the tape, thetransfer medium, having a greater affinity for the slide than to thetape, is cured and firmly affixed with the smear to the slide in amanner to transfer the smear to the slide.

Each such laminate including a tape portion leaving the platen 18 isdirected by the tape 10 over the idler roller 20 which bends the tapedelaminating it from the slide as the tape passes to the collectionspool 22. Such delaminating shown in FIG. 1 may be facilitated byeventual engagement of the underside of each slide 25 with an edge of achute 46 directing the slides one after another to a suitablenonillustrated collection container. A transferred smear permeated andencapsulated in the above-described manner is indicated at 48 in FIG. 6.Such a transferred smear, permanently mounted to a slide, is incondition for examination under a microscope. While not shown ordescribed heretofore, it will be apparent to those versed in the artthat any convenient identification system may be employed to identifythe donor or origin of each such transferred smear. It is also to beunderstood that the smear transfer technique of the invention is notlimited to the specific physical and chemical properties of thesmear-carrying substrate and the smear-receiving element or elementsdescribed herein.

While several forms of the apparatus and method for transferring abiological smear have been described, it will be apparent, especially tothose versed in the art, that such apparatus and method may take otherforms and are susceptible to various changes in details withoutdeparting from the principles of the invention.

What is claimed is:
 1. Transfer apparatus for transferring a pluralityof discrete biological cellular smears of blood from a substrate to abacking element, comprising:(a) substrate element having a firstsurface, (b) a plurality of smears of biological cellular material, (c)said biological cellular smears being positioned on said first surfaceof said substrate element in spaced relationship, (d) means adapted andconstructed to move said substrate element along a predetermined path,(e) a plurality of backing elements each having a first surface, (f)supply means for said backing elements, (g) means adapted andconstructed to move said backing element in proximity to said path andin opposing surface relationship with said first surface of saidsubstrate element, (h) transfer medium, (i) said transfer medium beingtransparent and exhibiting a refractive index substantially that of saidsmear of biological cellular material, (j) means adapted and constructedwhen said transfer apparatus is operated to introduce along said pathsaid transfer medium between the first surface of said backing elementand the first surface of said substrate element in sufficient quantityto essentially encapsulate said smears of biological cellular material,(k) means adapted and constructed when said transfer apparatus isoperated to sandwich said transfer medium between said first surface ofsaid substrate element and said first surface of said backing elementalong said path whereby said smears of biological cellular material areencapsulated within said transfer medium, (l) means adapted andconstructed when said transfer apparatus is operated to part saidbacking element from said substrate element along said path, (m) saidtransfer medium having sufficient adhesive properties whereby saidtransfer medium is selectively adhered to said first surface of saidbacking element and said smears of biological cellular matrial adhere tosaid transfer medium when said transfer apparatus is operated. 2.Transfer apparatus as defined in claim 1 wherein said smear ofbiological cellular material comprises a smear of blood.
 3. Transferapparatus as defined in claim 2 wherein said transfer medium is a liquidadhesive.
 4. Transfer apparatus as defined in claim 3 wherein saidsubstrate element is an elongated flexible element and said backingelement is substantially rigid.
 5. Transfer appparatus as defined inclaim 4 wherein the transfer medium is hardenable and means is providedfor hardening said transfer medium.
 6. Transfer apparatus as defined inclaim 5 wherein said transfer medium comprises a thermally polymerizablematerial.
 7. Transfer apparatus as defined in claim 5 wherein saidtransfer medium comprises a photopolymerizable material.